1. Field of the Invention
This invention relates, in general, to sewing machines and, in particular, to a new and useful sewing machine having a work support column with a cover construction for the column which may be opened and closed in a simple manner.
In known sewing machines with a work support column, the looper arranged at the upper end of the support column is covered by means of a flap pivotable about a horizontal axis. The cover flap is retained in the closing position by a ratchet mechanism provided with a leaf spring. To expose the looper, the operator grips the two opposite faces of the cover flap and pivots the flap about its axis into the open position, for which the holding force of the ratchet mechanism must be overcome at the beginning. As the cover flap is adapted to the form of the support column and is therefore greatly rounded, it is hard to take hold of it, even if fluted or roughened grip areas are provided. It may happen, therefore, that if the leaf spring is greatly tensioned, the operator's hand will slip off the cover flap or that a disproportionately high force must be applied to overcome the holding force of the ratchet mechanism.
2. SUMMARY OF THE INVENTION
The invention provides a sewing machine in which the cover flap can be pivoted into the open position in a simple manner and with little force.
The cover flap is designed so that, in the closing position thereof, one of the two bearing faces lying in the area of the axis and extending substantially at right angles to each other is turned toward the locking and actuating member. The locking and actuating member comprises an abutment face extending crosswise to the force direction of the spring, which face is thus directed substantially parallel to the corresponding bearing face of the cover flap. Due to this design or correlation of the cover flap and of the locking and actuating member, the spring associated with the locking and actuating member holds the cover flap counter to the action of the comparatively weaker spiral spring in the closing position. To expose the looper in the support column the locking and actuating member, expediently provided with a handle, is shifted counter to the force of the spring associated with it from the locking position into a release position, whereupon the spiral spring pivots the cover flap into the open position. The displacement of the locking and actuating member can be carried out by the operator by the movement of a finger alone, which is much simpler and easier than the gripping of the hard-to-grip cover flap and the manual overcoming of the holding force of a ratchet mechanism.
According to a further aspect of the innovation, the locking and actuating member touches, when the cover flap is in closing position, the bearing face thereof turned toward the locking and actuating member with spacing from the axis to be measured crosswise to the force direction of the spring. As a result, the spring exerts on the cover flap present in closing position, via the locking and actuating member, a continuously acting torque, by which the cover flap is pressed permanently against the work support column. In this way, it is prevented that the cover flap can vibrate during operation of the sewing machine and cause noise.
In a sewing machine in which there is arranged in the area of the work support column a cutting device with a vertically extending knife shaft, a particularly advantageous structural design of the innovation is characterized in that the locking and actuating member and the spring designed as compression spring are arranged on the knife shaft.
Accordingly, it is an object of the invention to provide a cover construction for a sewing machine which includes a work support column below a sewing thread guide needle and which includes an upright support member with a substantially L-shaped cover member having a side forming portion pivotally supported on the support member and a cover plate portion and wherein the side forming portion has bearing faces defined on the back and bottom thereof respectively which are substantially at right angles to each other and further including a locking member displaceably positioned on the support member and having an upper, substantially horizontal bearing face adapted to bear against the side wall bearing face when the cover is in an open position and to bear against the bearing face on the bottom of the cover member when the cover member is closed and the bottom surface is oriented substantially horizontally and which further includes a first spring acting on the locking member to urge it against the cover to engage the bearing surface of the locking member with the respective bearing faces on the cover member and a second spring acting on the cover to rotate it to an open position.
A further object of the invention is to provide a cover construction particularly for sewing machines which is simple in design, rugged in construction and economical to manufacture.
For an understanding of the principles of the invention, reference is made to the following description of typical embodiments thereof as illustrated in the accompanying drawings.